for ($x = 0; $x < $this->thumbnail_width; $x++) {
                            for ($y = 0; $y < $this->thumbnail_height; $y++) {
                                $AlphaChannelPixel = phpthumb_functions::GetPixelColor($img_alpha_mixdown_dither, $x, $y);
                                if ($AlphaChannelPixel['red'] > 127) {
                                    imagesetpixel($this->gdimg_output, $x, $y, $TransparentColor);